/*
 * Copyright (C) 2013 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef Bag_h
#define Bag_h

namespace WTF {

    template<typename T>
    class Bag {
    WTF_MAKE_NONCOPYABLE(Bag);
    WTF_MAKE_FAST_ALLOCATED;
    private:
        class Node {
        WTF_MAKE_FAST_ALLOCATED;
        public:
            template<typename... Args>
            Node(Args &&... args)
                    : m_item(std::forward<Args>(args)...) {
            }

            T m_item;
            Node *m_next;
        };

    public:
        Bag() {
        }

        Bag(Bag<T> &&other) {
            ASSERT(!m_head);
            m_head = other.m_head;
            other.m_head = nullptr;
        }

        Bag &operator=(Bag<T> &&other) {
            m_head = other.m_head;
            other.m_head = nullptr;
            return *this;
        }

        ~Bag() {
            clear();
        }

        void clear() {
            while (m_head) {
                Node *current = m_head;
                m_head = current->m_next;
                delete current;
            }
            m_head = nullptr;
        }

        template<typename... Args>
        T *add(Args &&... args) {
            Node *newNode = new Node(std::forward<Args>(args)...);
            newNode->m_next = m_head;
            m_head = newNode;
            return &newNode->m_item;
        }

        class iterator {
        public:
            iterator()
                    : m_node(0) {
            }

            // This is sort of cheating; it's equivalent to iter == end().
            bool operator!() const { return !m_node; }

            T *operator*() const { return &m_node->m_item; }

            iterator &operator++() {
                m_node = m_node->m_next;
                return *this;
            }

            bool operator==(const iterator &other) const {
                return m_node == other.m_node;
            }

            bool operator!=(const iterator &other) const {
                return !(*this == other);
            }

        private:
            template<typename U> friend
            class WTF::Bag;

            Node *m_node;
        };

        iterator begin() {
            iterator result;
            result.m_node = m_head;
            return result;
        }

        iterator end() { return iterator(); }

        bool isEmpty() const { return !m_head; }

    private:
        Node *m_head{nullptr};
    };

} // namespace WTF

using WTF::Bag;

#endif // Bag_h

